This invention relates generally to sound synthesis, and more particularly concerns choralizing method and apparatus wherein a tone is diffused into a family of tones within a narrow frequency band.
In music the distinction between a solo instrument and a group or section of the same instrument, i.e. a number of the same instrument playing in unison is an essential musical effect. Such a group we call a chorus of that instrument. Thus, the string section of an orchestra may consist of, say 16 first violins, 14 second violins, 12 violas, 10 cellos and 8 basses. This constitutes a string section chorus, and each group of the same instrument is a chorus of that instruction. Likewise, a vocal chorus may consist of 120 singers, performing in, say four or more parts. A violin section or chorus is easily distinguished from a single violin, even though heard at the same loudness. A four part chorus is easily distinguished from a vocal quartet.
The musical distinction may be likened to a tapestry, wherein the choral part is like a background, while the solo part is a detailed figure or design. Both design and background are necessary; both solo and chorus are useful.
In many cases of musical ensemble, the size of group must be reduced, either because of the cost of the performers, or because of the size of the performing space, as in an orchestra pit in a theater, or in a small recording studio. Thus, for example, a normal string section of 60 may be reduced to 15 players. The loss of volume may be recovered by amplification. But the loss of chorus effect cannot generally be recovered. The difference in sound beween 8 cellos and 2 can be easily detected. It would be very desirable to recover the chorus effect. Furthermore, one never hears, for example, a chorus of oboes, and the effect might be very useful musically. Thus, new and interesting musical effects may be made available by a choralizing process.
The distinction between a chorus and a solo instrument is physically explained. Ten violins playing in unison do not play exactly the same pitch; nor do any two have exactly the same quality. Thus, a very complex beating effect between each instrument and all others is set up, wherein each instrument loses its individual identity and a sort of shimmering effect occurs, wherein one hears the same musical progression or melody, and recognizes the quality of the instrument, but loses the solo nature.